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This quantity exceeds expenditures on school and apprenticeship, making breastfeeding possibly the largest source of human capital investment in early modern England. Yet the relative value of unpaid breastfeeding gradually declined as the wider economy grew. Indeed, for much of English history the income elasticity of breastfeeding appears to have been negative, only becoming positive at some point in the nineteenth century. Because breastfeeding was strongly negatively correlated with infant mortality, this challenges longstanding assumptions about the relationship between income and mortality. In sum, breastfeeding was not a biologically determined constant but a dynamic, if neglected, part of economic life.<\/jats:p>","DOI":"10.1073\/pnas.2600844123","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T19:12:05Z","timestamp":1790017925000},"update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":0,"title":["Valuing five centuries of unpaid breastfeeding in England"],"prefix":"10.1073","volume":"123","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-3560-4186","authenticated-orcid":false,"given":"Louis","family":"Henderson","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/0090zs177","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Economic History, London School of Economics and Political Science","place":["London, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3808-5236","authenticated-orcid":false,"given":"Jane","family":"Humphries","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/0090zs177","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Economic History, London School of Economics and Political Science","place":["London, United Kingdom"]},{"id":[{"id":"https:\/\/ror.org\/052gg0110","id-type":"ROR","asserted-by":"publisher"}],"name":"All Souls College, University of Oxford","place":["Oxford, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2026,9,21]]},"reference":[{"key":"e_1_3_4_1_2","doi-asserted-by":"publisher","DOI":"10.1177\/13872877251326231"},{"key":"e_1_3_4_2_2","doi-asserted-by":"publisher","DOI":"10.1111\/ehr.13323"},{"key":"e_1_3_4_3_2","volume-title":"The First Industrial Woman","author":"Valenze D.","year":"1995","unstructured":"D. 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